Method of offering wall-thickness thinning prediction information, and computer-readable recording medium storing wall-thickness thinning prediction program, and method of planning piping work plan

ABSTRACT

A wall-thickness thinning rate at a not-measured position is estimated using information having a small number of measured points. Simulation of behavior of fluid flowing inside a pipe line is performed based on wall-thickness data of pips and three-dimensional layout data of the pipe line including the pips using a computer, and simulated wall-thickness thinned data of the pipes composing the pipe line is calculated from change of the simulated behavior of fluid.

This is a continuation application of U.S. Ser. No. 11/068,919, filedMar. 2, 2005, which is a continuation application of U.S. Ser. No.09/813,914, filed Mar. 22, 2001.

BACKGROUND OF THE INVENTION

1. Field to which the Invention Belongs

The present invention relates to a technology of estimating lifetime ofpiping parts in a process plant, and a technology of forming a replacingwork plan of piping parts using a result of the lifetime estimation.

2. Prior Arts

As disclosed in Japanese Application Patent Laid-Open Publication No.Hei 8-178172 titled “a method of calculating and evaluatingwall-thickness thinning of a component and piping system caused byerosion-corrosion” and U.S. Pat. No. 4,935,195 titled “corrosion-erosiontrend monitoring and diagnostic system”, a conventional maintenance formof a process plant is that a maximum progressed value of pipewall-thickness thinning for each of the piping parts is predicted byforming a wall-thickness estimation formula using various kinds ofinformation necessary for wall-thickness control, particularly awall-thickness measurement database and a document database(temperature, pressure, dissolved oxygen concentration, flow speed ofthe fluid flowing inside the pipe). Further, an inspection plan and areplacing work plan are made for each of the estimated piping parts.

In the conventional technology, by focusing only on an individual pipingpart such as one elbow or one straight pipe, the wall-thickness thinningprediction has been performed based on past wall-thickness thinningmeasured data. However, neither of the three-dimensional layout of thepart nor the kind and the shape of a part adjacently connected to thepart has been taken into consideration.

Because the piping parts (piping (elbow, straight pipe, reducing pipe,branch pipe and so on), valve, pump and so on) composing a process plantare disposed differently in three-dimension even if they are the samekind of parts, have the same shape and are made of the material,behavior of the fluid flowing through the parts is substantiallydifferent depending on a position where the parts are disposed and on akind of a part to which the part is connected.

Therefore, The wall-thickness thinning rate of the piping part is varieddepending on the behavior of the fluid flow. Further, durability of aplant part composing the process plant is different depending on thethree-dimensional layout of the plant part and on a kind of a part towhich the plant part is connected, and also depending on a condition ofthe fluid flowing inside the plant part and on number of plantshutdowns.

Therefore, the prior art can not have performed wall-thickness thinningprediction which takes into consideration change in the behavior of thefluid flowing through the whole pipe lines composing the process plant,and can not make an efficient plan for-replacing the piping parts basedon the prediction result.

Further, the prior art can not have performed wall-thickness thinningprediction on a unmeasured part even within one pipe, and can not haveperformed lifetime prediction of piping parts and wall-thicknessthinning prediction of piping parts composing the whole process plant.

Further, in a conventional plan of replacing parts, in a case wherereplacing periods of the piping parts are different from one another,the piping part replacing work must be frequently performed for thereplacing work corresponding to each of the piping parts. Accordingly,since each time of the replacing work needs preparation associated tothe work and shutdown of the plant operation, an economical loss causedby a large cost spent in the preparation and reduction of operabilityassociated with the plant shutdown if the repairing work often occurs.

This is caused by that lifetime of piping parts of the whole processplant has not been accurately known when the replacing work plan usinglifetime estimation and wall-thickness thinning estimation of parts suchas pipes composing the process plant is made.

SUMMARY OF THE INVENTION

An object of the present invention is to perform a highly accuratewall-thickness thinning prediction.

Another object of the present invention is to make it possible toperform a wall-thickness thinning prediction of a piping part differentfrom a piping part of which the wall-thickness thinning value is notmeasured.

A further object of the present invention is to provide the estimatedwall-thickness obtained as described above to a client.

Further, another object of the present invention is to make it possibleto plan a replacing work plan which taking into consideration lifetimeand estimated thinned wall-thickness of each of parts composing thewhole pipeline or the whole process plant from the above-describedestimated results, and to provide estimated wall-thickness obtained asdescribed above to a client.

Further, another object of the present invention is to make it possibleto plan an economical replacing work plan for purpose of long termoperation by reducing number of times of replacing work for the pipingparts of the whole process plant.

Furthermore, another object of the present invention is to make itpossible to plan a low-cost and long term plant maintenance plan takinginto consideration cost required for the work as well as simply reducingthe number of times of replacing the piping parts.

A further object of the present invention is to provide the replacingwork plan obtained as described above to a client.

A feature of the present invention is as follows.

Initially, wall-thickness data of piping parts of an objective processplant is measured, or measured results of wall-thickness data arereceived from a client, and the data is stored in a DB (database).

Fluid data in the piping of the process plant expressing an initialcondition of the fluid flowing in the pipe line and three-dimensionallayout data of the piping parts are measured or measured received from aclient, and the data is pre-stored in a DB.

Next, layout of the piping parts and wall-thickness and shape of each ofthe piping parts are obtained from the three-dimensional layout data ofpiping parts.

An amount of thinned wall-thickness is calculated from the thicknessobtained from the three-dimensional layout data and the measuredthickness data, and a wall-thickness thinning rate per unit time iscalculated from a used time of the piping line and the obtained amountof thinned wall-thickness.

Behavior of fluid flowing in the piping part is estimated from a patternof the wall-thickness thinning rate or the amount of thinnedwall-thickness.

Swirl flow data of the fluid flowing the whole pipe line including thepiping part is calculated from the behavior of fluid flowing in thepiping part and the initial condition shown by the fluid data.

Shear stress values in various positions of the pipe line by performingfluid simulation based on the swirl flow data.

A ratio of a wall-thickness thinning at a wall-thickness measuredposition to a shear stress at the wall-thickness measured position amongthe calculated shear stress values is obtained. In detail, the ratio ofa wall-thickness thinning per unit shear stress is calculated bydividing a wall-thickness thinning rate by a shear stress.

An estimated wall-thickness value in each position of the pipe line canbe calculated by multiplying the ratio of a wall-thickness thinning perunit shear stress to a shear stress in each position of the pipe line.

If a pipe line has no measured position, a shear stress of swirl flowflowing through the pipe line. If there is a pipe line similar to thepipe line, an estimated wall-thickness of the pipe line is calculatedusing a wall-thickness thinning ratio at the wall-thickness measuredposition to the shear stress at the wall-thickness measured position ofthe similar pipe line.

If the is no similar pipe line, an estimated wall-thickness of the pipeline is calculated by setting a wall-thickness thinning ratio at aposition having the maximum shear stress as an average value ofwall-thickness thinning ratio at the wall-thickness measured position tothe shear stress at the wall-thickness measured position of the pipeline of which the wall-thickness has been measured.

In the present invention, since simulation of the behavior of the fluidflowing in the pipe line and the wall-thickness thinning caused by thebehavior of the fluid is performed as described above, thewall-thickness thinning not only of the piping parts of which thewall-thickness values are measured, but also of the piping parts of thewhole pipe line can be estimated.

Further, by making a work plan for replacing the piping parts based onthe estimated wall-thickness thinning results including the estimatedwall-thickness thinning results other than the piping parts of which thewall-thickness values are measured, the piping parts to be replaced atthe same period can be specified. Therefore, an efficient replacing workplan (a replacing work plan capable of suppressing number of plantshutdown times) of the piping parts in the whole pipe line can be made.

Furthermore, by forming combination of the piping parts capable ofreducing the total work cost by performing replacing work at a time in adatabase, the cost required for the one time of the replacing work canbe suppressed by making the replacing work plan using the combinationstored in the database.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing the configuration of a servicesupplier system in which the present invention is used;

FIG. 2 is a detailed block diagram showing the service supplier system;

FIG. 3 is a flow diagram of a pipe wall-thickness thinning estimationprocess;

FIG. 4 is a flow diagram of Process 1;

FIG. 5 is a flow diagram of Process 2;

FIG. 6 is a flow diagram of Process 3;

FIG. 7 is a table showing three-dimensional layout information;

FIG. 8 is a table showing wall-thickness measurement data;

FIG. 9 is a table showing in-pipe fluid data;

FIG. 10 is a flowchart showing a fluid behavior estimation processingpart;

FIG. 11 is a flowchart showing a fluid simulation processing part;

FIG. 12 is a flowchart showing an input fluid data generation processingpart;

FIG. 13 is a detailed block diagram showing the replacing work planplanning processing;

FIG. 14 is a diagram showing the processing flow of the replacing workplan planning processing;

FIG. 15 is a diagram showing the processing flow of the replacing timingcombination generating part;

FIG. 16 is a diagram showing the processing flow of the maintenance costcalculation part;

FIG. 17 is a diagram showing the processing flow of the optimum workplan determining part;

FIG. 18 is a table showing three-dimensional piping information;

FIG. 19 is a view showing a pipe line;

FIG. 20 is a table showing replacing timing plan data;

FIG. 21 is a table showing material amount data;

FIG. 22 is a table showing job hour data;

FIG. 23 is a table showing job procedure data;

FIG. 24 is a flowchart showing generation of the job procedure data;

FIG. 25 is a job man-hour vs. non-operational period table;

FIG. 26 is a job man-hour vs. job cost table;

FIG. 27 is loss per day during non-operational period;

FIG. 28 is a material cost table;

FIG. 29 is a job man-hour data table;

FIG. 30 is a table showing electric power loss data;

FIG. 31 is a table showing total material cost data;

FIG. 32 is a table showing total cost data;

FIG. 33 is a flowchart showing the processing of the maintenance costcalculation part;

FIG. 34 is a flowchart showing the processing of the maintenance costcalculation part;

FIG. 35 is a table showing omissible job data; and

FIG. 36 is a block diagram showing the flow of generating omissible jobman-hour data.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Initially, description will be made on a design of a process plant.

Designing of a process plant is generally performed by initiallydetermining positions of installing large components, and thenperforming logical design connecting between the large components so asto satisfy the target function. This is generally called as systemdesign. For example, in a case of performing logical design ofgenerating steam, an apparatus for making water to a high temperatureand high pressure state is initially connected to a steam generator forextracting steam with piping, and after generating the steam, a logicaldiagram transporting the steam to a turbine blade rotary apparatus withpiping is formed.

Therein, pipes made of materials having a function capable ofwithstanding high pressure and having high heat insulation property areselected and arranged from the apparatus for making water to a hightemperature and high pressure state to the steam generator, and pipingparts gradually reducing the diameter of the piping are selected andarranged from the steam generator to the turbine blades in order toincrease the steam velocity. System design in process plant is todetermine arrangement of the piping parts between the plant componentssuch as the steam generator and the steam turbine, as described above.

When the system design is performed, a minimum unit performing thelogical design for the identical purpose is called as one piping system.

Further, the piping system is usually composed of a plurality of pipes,not a single pipe, in taking the steam generation efficiency intoconsideration. A line number of each of the pipes is set as anidentifier. That is, one piping system is composed of a plurality ofpipes each having an individual line number.

Further, layout design for spatially disposing the logically designedpiping is performed. The layout is performed line-number by line-number.

Further, installation work is performed by pre-dividing the pipe in alength of 1.5 m to 2.0 m to be brought in and then joining the pipesections by welding or the like so as to make the construction andinstallation easy. This minimum unit of pipe is called as a piping part.

Next, a feature when the present invention is embodied will be describedbelow in detail.

FIG. 1 is a block diagram showing the total system in which the presentinvention is used.

The present system is composed of a service supplier system 110, aclient system 120 and a vendor system 130.

The client system 120 comprises a communication unit 121 connected tothe service supplier system with a communication line; a DB 123 storingthree-dimensional layout data on piping parts composing the plant,wall-thickness measurement data obtained by measuring wall-thickness ofthe pipes and in-pipe fluid data on fluid flowing the pipes; and ainformation processor 122 for performing processing to send the data inthe DB 123 through the communication unit and processing to receivinginformation from the service supplier system 110.

The construction of the vendor system 130 is similar to that of theclient system 120.

The service supplier system 110 is composed of a communication unit 111for performing communication with the client system 120 and the vendorsystem 130; a database 113; a display unit 114; and an informationprocessor 112 for performing main processing of the service suppliersystem, the information processor being connected to the communicationunit 111 and the database 113 and the display unit 113 and an inputunits such as a keyboard and so on.

As processing to be executed by the information processor 112, There arepipe wall-thickness thinning prediction processing 115 and replacingwork plan planing processing 116. These are processed by executingprograms on OS, and these programs are installed programs stored in arecording media or installed by being downloaded through the Internet tothe information processor 112.

FIG. 2 is a detailed block diagram showing the service supplier system.

The DB 113 is composed of a database 201 storing the three-dimensionallayout information (FIG. 7) of the piping parts; a database 202 storingmeasured data (FIG. 8) of measured wall-thickness of the piping parts;and a database 203 storing data in regard to fluid flowing inside thepipes (in detail, kind of fluid, average flow velocity, pressure,temperature, oxygen ion concentration, metal ion concentration: FIG. 9)is recorded.

A pipe wall-thickness thinning prediction system 115 for predictingwall-thickness thinning of the pipe line by reading in thewall-thickness prediction program stored in a recording medium iscomposed of a fluid behavior estimation processing part 241; a fluidsimulation processing part 242; an input fluid data generationprocessing part 243 for generating fluid data at a position near theinlet position of the piping part; and a selection output part 207 forselecting and outputting a position having a high pipe wall-thicknessthinning rate.

The selection output part 207 performs processing not only fordisplaying on the display unit 114, but also for sending the clientsystem 120 through the communication units 111 and 121 and for sendingthe vendor system 130 through the communication units 111 and 131.

The replacing work plan planing processing 116 is to be explained later.Initially, the processing of the pipe wall-thickness thinning predictionprocessing 115 will be described below, referring to FIG. 3.

The processing is performed initially by searching and checking whetheror not there are three-dimensional layout data on pipes of an objectiveplant, fluid data on fluid flowing in the pipe line and wall-thicknessmeasured data (Process 3). If not, the data is received by requestingthe data to the client system 120 through the communication unit 120(Process 302).

Next, as a piping part ID is input from the keyboard or the mouse 94,the piping part ID is directly input to the fluid simulation processingpart 205 (through the communication units 111 and 121). The fluidsimulation processing part 205 reads the piping three-dimensional layoutinformation of the piping of the objective plant from the DB 201, andselects a pipe line including the input piping part ID, and searchespiping parts contained in the pipe line using the part ID as the key(Process 303).

Therein, the piping three-dimensional information of the DB 202 ismanaged the piping based on part ID, position information, connectioninformation, shape, material, system number, pipe line number andmeasured wall-thickness data ID. Therefore, the input piping part ID canbe used as a key to search the corresponding pipe line number, and thepipe line number can be further used as a key to search the part IDSincluded in the pipe line.

Next, based on the piping part ID of the wall-thickness measured data ofthe DB 202, it is judged based on presence or absence of the measuredwall thickness data number in the piping three-dimensional layoutinformation whether or not the pipe line including the selected pipepart includes any piping part of which wall-thickness thinning value hasbeen measured (Process 304).

If the check result is that there is a piping part of whichwall-thickness thinning value has been measured on the pipe line,Processing 1 is executed.

If there is no piping part of which wall-thickness thinning value hasbeen measured on the pipe line, it is checked whether or not there isany similar pipe line (Process 305).

The similarity here is judged by that the pipe line is in the samesystem, and that the diameter of the pipe and the average velocity offluid flowing in the pipe are within a certain range.

If there is any similar pipe line, Processing 2 is executed. If there isno similar pipe line, Processing 3 is executed. Therein, Processing 1 toProcessing 3 are for calculating estimated wall-thickness of a selectedpipe line using data stored in the DBs 201 to 203.

After executing processing 1 to 3, it is checked whether or nor there isany still-not-analyzed pipe line (Process 309).

If there is any still-not-analyzed pipe line, the processing is returnedto Process 302. If not, the processing proceeds to the next Process 310.

After completing all of the pipe lines, the estimated wall-thicknessresult is displayed.

At that time, in the selection output part, a piping part having awall-thickness value thinner than a preset value is displayed on thedisplay unit 114 by changing color in order to enhancement (Process310).

After that, the result is sent to the client, and the replacing workplan planning processing 116 is to be executed.

The Processing 1 to Processing 3 described above will be describedbelow.

Initially, the data stored in the DBs 201 to 203 are read.

FIG. 4 is a flowchart showing the outline of Processing 1.

Firstly, in the fluid behavior estimation part 204, a swirl direction ofthe fluid flowing in the pipe and an axial direction are obtained(Process 401). This process 401 is performed according to the flow shownin FIG. 10.

The wall-thickness measurement data contained in the selected pipe lineis selected out of the wall-thickness measurement database 202 using thecorresponding measured wall-thickness data ID as the key (Process 1001).Next, the maximum and the second maximum wall-thickness thinnedpositions among the measured wall-thickness data are searched from theinput wall-thickness thinned position data (Processes 1002, 1003).

The maximum wall-thickness thinned position is connected to the secondmaximum wall-thickness thinned position with a line segment (Process1004), and an angle of the line segment to the axial direction of thepipe is calculated (Process 1005). This obtained angle is let to be theswirl flow of the fluid at a position near the piping part of which thethickness is measured.

Next, swirl flow data is generated in the fluid data generating part(Process 402).

As shown in FIG. 12, the swirl angle cos θ, sin θ obtained in the fluidbehavior estimation processing part is searched (Process 1201), andvirtual particles are aligned in the inlet of the pipe, and Poiseuilleflow velocity is given to in the vertical direction of the cross sectionof the pipe, and the other velocity components are given by cos θ, sinθ.

Further, in the fluid simulation processing 242, a shear stress at themaximum wall-thickness thinning position is calculated to obtain thewall-thickness thinning rate per unit shear stress (Process 403). Theprocessing flow shown in FIG. 11 is used for performing these processes.That is, the three-dimensional layout information of the pipe on thepipe length and the pipe diameter is retrieved from the DB 201.

Then, the average velocity and the viscosity of the fluid are read fromthe in-pipe fluid database 203 using the piping part ID as the key. Thepipe length, the pipe diameter, the average velocity and the viscosityread are substituted into individual terms of Equation 3 to calculatethe velocity distribution in the piping part, and a shear stress iscalculated by differentiating the velocity with respect to the normalcomponent of the inner wall surface and by multiplying a constantdetermined by the viscosity, as shown by Equation 4.

Next, the wall-thickness measured data is retrieved from the DB 202, andan amount of wall-thickness thinning is calculated by subtracting thewall-thickness from the wall-thickness data value stored in thethree-dimensional layout data, and a wall-thickness thinning rate iscalculated by dividing the amount of all-thickness thinning by the useperiod of the pipe. Then, a wall-thickness thinning rate per unit shearstress is calculated by dividing the wall-thickness thinning rate by theobtained shear stress. $\begin{matrix}{V = {\frac{\Delta\quad p}{4\quad\eta\quad l}\left( {R^{2} - r^{2}} \right)\left( {l,{\cos\quad\theta},{\sin\quad\theta}} \right)}} & \left( {{Equation}\quad 3} \right) \\{\sigma = {k\frac{\delta\quad V}{\delta\quad y}}} & \left( {{Equation}\quad 4} \right)\end{matrix}$

There, σ is a shear stress, k is a constant, and y is a component normalto the inner wall.

Analysis is performed to the piping parts of which the wall-thicknessvalues are not measured, on the pipe line in the fluid simulationprocessing part in order to calculate shear stresses acting onindividual piping parts.

The wall-thickness thinning rate for each of the piping parts iscalculated by multiplying the wall-thickness thinning rate per unitshear stress to the shear stress for each of the piping parts, as shownby Equation 5 (Process 404) $\begin{matrix}{S = {\sigma\frac{S_{l}}{\sigma_{l}}}} & \left( {{Equation}\quad 5} \right)\end{matrix}$

There, S₁ is the wall-thickness thinning rate at the maximum measuredwall-thickness thinned position, and σ₁ is the shear stress at themaximum measured wall-thickness thinned position. An estimatedwall-thickness in the future is calculated by multiplying a period tothe wall-thickness thinning rate.

In the fluid simulation processing part 205, the fluid analysis isexecuted through the method that the fluid behavior is expressed byparticles and paths of the particles are traced by calculating themotion of the particles in the three-dimensional pipe by the product ofthe velocity and the elapsed time. At that time, the swirl angle(direction) obtained by the fluid behavior estimation part is searched(Process 1201).

Virtual particles are aligned in the inlet of the corresponding pipe,and Poiseuille flow velocity is given to in the vertical direction ofthe cross section of the pipe, and the other velocity components aregiven by cos θ, sin θ, and the searched swirl angle is substituted intothe θ. Then, when the particle collide against the inner wall of thepipe, the particle is elastically reflected and the collision position(coordinate values) is output. The shear stress is identified thevelocity of the collision particle and number of collisions per unittime and per unit area.

Here, description will be made on that the swirl flow is used in thefluid simulation, referring to Equation 3.

The velocity of the fluid flowing in the pipe is fast at a positiondistant from the inner wall of the pipe due to the effect of a viscousforce acting on the inner wall of the pipe. The motion of the fluid canbe expressed by the partial differential equation called asNavier-Stokes equation. $\begin{matrix}{{\frac{\delta\quad V}{\delta\quad t} + \left( {V \cdot {grad}} \right)} = {{{- \frac{1}{\rho}}{gradp}} + {\frac{\eta}{\rho}{\nabla^{2}V}}}} & \left( {{Equation}\quad 1} \right)\end{matrix}$

There, V is a velocity vector, t is time, v is a velocity, ρ is adensity, p is a pressure, and η is a viscosity.

That is, the equation of motion can be expressed by the sum of theadvection term expressing the effect of flicking out the surroundingfluid particles by an inertia force of the fluid; the diffusion termexpressing the effect of retarding the speed of the surrounding fluidparticles by an intermolecular force; and the pressure gradient termexpressing the effect of giving a forward moving force to the fluidparticles.

Although the motion of the fluid is unstable because the advection termexpressing the effect of flicking out the fluid particles is non-linear,the diffusion term acts so as to stabilize the flow. Therefore, themagnitude of the diffusion term strongly affect the whole behavior ofthe fluid.

Since the boundary of the flow in the pipe is enclosed with the pipe,the constraint is strong and accordingly the flow is stabilized comparedto a flow in an open space. An ideal flow in the pipe is of a quadraticparabolic flow distribution called as Poiseuille flow.

As a solution of Navier-Stokes equation satisfying the Poiseuille flow,there is Equation 2. $\begin{matrix}{v = {\frac{\Delta\quad p}{4\quad\eta\quad l}\left( {R^{2} - r^{2}} \right)}} & \left( {{Equation}\quad 2} \right)\end{matrix}$

There, l is a length of the pipe, R is a radius of the pipe, and r is adistance form the center of the pipe.

However, since the section of the pipe is circular, the velocitydistribution is symmetrical. The velocity is mathematically stable, butphysically unstable. An example of the evidence is that a ball ofbaseball flies on a more stable path when the ball is rotated.

Since the boundary of the flow is surrounded by the inner wall of thepipe, the flow distribution rarely becomes the ideal Poiseuille flowhaving symmetry, but the inside flow becomes a stable swirl-dominantflow. Therefore, it is assumed that the swirl flow is the quadraticparabolic flow distribution of Poiseuille flow which is rotating in thecircumferential direction of the pipe, and accordingly it has decidedthat the rotating angle is determined from the wall-thickness thinningtendency of the measured pipe.

Therefore, Equation 2 is converted to Equation 3.

Although small fluctuations in the fluid velocity actually occureverywhere, the main factor of the shear stress to cause corrosionfatigue in the inner wall of the pipe is the swirl flow which is a maincomponent of the fluid flow. This is because the main factor of theshear stress to cause corrosion fatigue in the inner wall of the pipe isan impact force of the fluid against the inner wall of the pipe.

A stable oxide film (this is called as a passive film) is formed on themetal surface, but after initiation of the plant operation, the passivefilm is peeled off by the impact force of the fluid flowing inside thepipe. Because the metal is directly exposed to the fluid at the positionwhere the passive film is peeled, both of an anode reaction ofdissolving metallic ions into the fluid and a reaction of forming thepassive film occur at a time.

On the other hand, a chemical reaction of consuming electrons on thepassive film occurs as a cathode reaction. When the anode reaction ofdissolving the metal ions is dominant to the reaction of forming thepassive film, a phenomenon of progressing corrosion called aswall-thickness thinning occurs.

On the contrary, when the reaction of forming the passive film isdominant, corrosion progresses from a point on the surface to the insideof the metal to cause a corrosion crack. The both kinds of corrosionscan be predicted if the peeling-off positions of the passive film can beidentified from the fluid behavior.

The flow of Processing 2 will be described below, referring to FIG. 5.

A correlation between the wall-thickness thinning rate and the shearstress of a similar pipe line (Process 501). The correlation here meansthe wall-thickness thinning rate per unit force of the shear stress.

In the fluid simulation processing part, the swirl flow data of the pipeline is calculated and the shear stress is calculated (Process 502), andthe wall-thickness thinning rate is calculated from the calculated shearstress and the correlation between the shear stress and thewall-thickness thinning rate in the similar pipe line (Process 503).These processes 502 and 503 are similar to that in the processes ofProcessing 1.

The estimated wall-thickness in the future is calculated by multiplyinga period to the wall-thickness thinning rate.

The flow of Processing 3 will be described below, referring to FIG. 6.

By performing fluid analysis on all the lines of the system in the fluidsimulation processing part (Process 601), the shear stress for eachswirl direction of the swirl flow to specify a position where the valueof the shear stress is high (Process 602).

It is assumed that the wall-thickness data at the high shear stressposition (the highest shear stress position) is the average value of themeasured wall-thickness data stored in the DB. Under the premise, thecorrelation between the wall-thickness thinning rate and the shearstress is calculated.

A wall-thickness thinning rate of each piping part in the pipe line iscalculated from the calculated correlation between the wall-thicknessthinning rate and the shear stress and the shear stress. The estimatedwall-thickness in the future is calculated using the wall-thicknessthinning rate.

The replacing work plan planning processing 116 will be described below.Before described the replacing work plan planning processing 116, amethod of planning a piping modification work plan for a process plantwill be described in detail, taking a nuclear plan as an example.Nuclear plant modification work is safely performed usually by closing avalve of a modification work zone to isolate from the other zones(system isolation). During the modification work period, operation ofthe plant is usually stopped in order to secure the safety.

On the other hand, the piping replacement in the nuclear plant isperformed in the procedure of “setting up of a “scaffold” necessary forthe replacing job; “decontamination job” for reducing the radiation dosein the pipe; “cutting” of the pipe line to be worked; “disposition” forcurrying out the cut piping part; “installation” for attaching a newpiping part; “welding” of the installed piping part; and finally“painting” for protecting the outside of the attached pipe from theenvironment. There are many jobs in each of the procedure processes.

Estimation of period and cost required for each job is necessary formaking the schedule plan. The job period and the job cost are calculatedbased on man-hours required for the job (job man-hour). The jobman-hours is expressed by a product of number of pipes (material amount)and working hours of workers (job cost).

That is, the job man-hours can be expressed by Equation 6.Job man-hours=(material amount)×(job cost)   (Equation 6)

Further, the schedule of the jobs other than the installation and thewelding may be reduced by commonly using the scaffold, and byeliminating work for preparing machines used for the jobs.

That is, in the jobs other than the installation and the welding, thereare jobs of which the man-hours do not depend on the material amount.Therefore, the job man-hours can be expressed by Equation 7.$\begin{matrix}{{{Job}\quad{man}\text{-}{hours}} = {\left( {\left( {{material}\quad{amount}} \right) \times \left( {{job}\quad{cost}} \right)} \right)_{{scaffold}\quad{set}} + \left( {\left( {{material}\quad{amount}} \right) \times \left( {{job}\quad{cost}} \right)} \right)_{decontamination} + \left( {\left( {{material}\quad{amount}} \right) \times \left( {{job}\quad{cost}} \right)} \right)_{cutting} + \left( {\left( {{material}\quad{amount}} \right) \times \left( {{job}\quad{cost}} \right)} \right)_{disposition} + \left( {\left( {{material}\quad{amount}} \right) \times \left( {{job}\quad{cost}} \right)} \right)_{installation} + \left( {\left( {{material}\quad{amount}} \right) \times \left( {{job}\quad{cost}} \right)} \right)_{welding} + \left( {\left( {{material}\quad{amount}} \right) \times \left( {{job}\quad{cost}} \right)} \right)_{painting}}} & \left( {{Equation}\quad 7} \right)\end{matrix}$

Further, a cost of work can be calculated by taking the work period andthe cost of employing workers during the work period based on the jobman-hours.

The total piping work cost can be calculated from Equation 8.$\begin{matrix}{{{Total}\quad{piping}\quad{work}\quad{cost}} = {{{work}\quad{cost}} + {{electric}\quad{power}\quad{loss}\quad{due}\quad{to}\quad{plant}\quad{shutdown}} + {{piping}\quad{material}\quad{cost}}}} & \left( {{Equation}\quad 8} \right)\end{matrix}$

Since the electric power loss and the work cost can be reduced byperforming replacement of plural pipes together at a time, the totalmaintenance cost during the plant servicing period can be optimized.

The system structure will be described below.

The DB 113 comprises the DB 1302 which stores the results of estimatingthe wall-thickness thinning of the piping parts performed by the pipewall-thickness thinning prediction processing 115, and the estimatedwall-thickness data to be output.

The estimated wall-thickness data is input to the replacing work planplanning processing 116 from the DB 1302.

The replacing work plan planning processing 116 is composed of areplacing timing combination generating part 1305, which makes aplurality of long-term plant maintenance plans by extracting andreceiving accurate lifetimes and remaining lifetime periods of the plantcomponents from the estimated wall-thickness data and by selecting plantcomponents to be modified in taking the lifetimes of the plantcomponents; a maintenance cost calculation part 1303, which calculatesthe costs required for the plant maintenance plans by calculating jobman-hours from the plant maintenance plan data and the job procedure,the piping material amounts and the job cost data, and by calculatingthe work cost from the job man-hours and the loss associated with theshutdowns during the work periods, and by summing the costs togetherwith the material costs; and an optimum work plan determining part 1304,which selects a maintenance plan optimizing the cost and the reliabilityduring the plant servicing period in taking needs of the client intoconsideration from all the plant maintenance plans after calculating andrecording all the maintenance costs for all the plans.

The processing flow executed in the replacing work plan planningprocessing 116 will be described below, referring to FIG. 14.

Initially, estimation of wall-thickness thinning of the piping parts isexecuted in the pipe wall-thickness thinning prediction processing 115,and the estimated wall-thickness data is stored in an area 1402 in apipe deterioration database 1302 as pipe deterioration data. The pipedeterioration data and the three-dimensional piping layout data areinput to the <replacing timing combination generating part 1305>, andall combinations of individual plant part replacing timings are output(Process 1403) and then stored in a replacing timing plan database 1404as work plan data.

The recorded work plan data is output to the <maintenance costcalculating part 1303>, and the maintenance costs for the individualwork plans are output (Process 1405), and stored in a life-cycle costdatabase of each of the work plans. The maintenance costs for theindividual work plans are input to the <optimum work plan determiningpart 1304>, and the most economical maintenance plan is determined amongthe individual work plans (Process 1407).

The construction of each of the processing parts in the replacing workplan planning processing and the processing flow will be described belowin detail.

Firstly, the <replacing timing combination generating part 1305> will bedescribed, referring to the processing flow of FIG. 15.

A pipe line is selected by inputting a piping part ID directly from thekey board or the mouse, or being sent through the communication units(Process 1501). A lifetime of the pipe part of the pipe line selectedusing the piping part ID as the key is extracted from the pipedeterioration database. The lifetime is input to the replacing timingcombination generating part. Further, N-number of piping part IDs on thepipe line including the piping part are automatically searched from thepipe deterioration database, and the information on the piping parts arealso input (Process 1502).

Next, a piping part having the shortest lifetime is searched from theN-number of piping parts having their lifetimes (Process 1504). Lettingthe lifetime of the piping part be a, years of m times of the lifetime a(m=0, 1, 2, 3 . . . ), that is, a×m year are set to a work period(Process 1505). Cases where the other parts cannot help being replacedduring the m-th work period are classified (Process 1506), and theclassified case combination is output as data shown in FIG. 20 andstored in the replacing timing plan database 1404.

The construction of the <maintenance cost calculating part 1303> will bedescribed below.

The <maintenance cost calculating part 1303> uses a material amountdatabase 1611 as shown in FIG. 21 which is extracted from thethree-dimensional information of piping; a job cost database 1612 whichis formed the working hours of workers (job cost) in each job of themaintenance work in a data form as shown in FIG. 22; a job proceduredatabase 1613 which is formed the job content for each work in a dataform as shown in FIG. 23; a job man-hour vs. non-operational periodtable 1614 which is formed the job area and the plant non-operationalperiod due to the work in a data form as shown in FIG. 25; a jobman-hour vs. job cost table 1615 which is formed the job amount (jobman-hour) and the job cost associated with the job man-hour in a dataform as shown in FIG. 26; a loss par-one-day-shutdown database 1616which is formed the loss per day associated with stopping the operationby closing the work area in a data form as shown in FIG. 27; and amaterial cost database 1617 in which costs per piping part are recordedas shown in FIG. 28.

The material amount database is formed by extracting data on lengths ofpipes from the piping part three-dimensional layout database 1301 andbeing formed in a data form of the length for each pipe as shown in FIG.21.

The job cost database records the summarized data in the data form ofthe job amounts for each job as shown in FIG. 22.

The job procedure data records the summarized data as shown in FIG. 23on whether or not a job accompanied by each of the plant componentshould be performed. Therein, the numeral 1 in the table expresses thatthe job should be performed, and the numeral 0 expresses that the jobshould not be performed. This processing is executed according to theflow shown in FIG. 24. Further, a z-coordinate is determined from thepipe coordinate by linking the three-dimensional layout database 1301and this database (Process 2401).

A height from the ground is determined and extracted, and it is judgedwhether or not the height is above 1 m (Process 2402). If above 1 m, thenumeral 1 is recorded in the scaffold job column in the job proceduredata (Process 2403). If below 1 m, the numeral 0 is recorded in thescaffold job column in the job procedure data (Process 2404).

The job man-hour vs. non-operational period table 1614 records thesummarized data as shown in FIG. 25 by empirically determining workperiods accompanied job man-hours from the job man-hours.

The job man-hour vs. job cost table 1615 records the summarized data asshown in FIG. 26 by calculating an empirical cost required for the jobman-hours in the job procedure. Further, this data may be always updatedin taking variations of prices and employment situation intoconsideration.

The loss par-one-day-shutdown database 1616 records the summarized dataof an electric power loss per day due to stopping of the operationassociated with the work as shown in FIG. 27.

The material cost database 1617 stores the summarized data of the pipecost as shown in FIG. 28 by searching the material, the diameter and thelength of the pipes from the three-dimensional database using the workobjective pipe ID as the key recorded in the memory 1607 (pipinginformation extracting processing).

Further, the material cost database 1617 can be connected to the vendorsystem through the communication unit, and accordingly can record theresent price and the delivery date of the piping parts using theinformation of the vendor. This system can make a work plan reflectingthe material delivery data and the market.

The processing flow of the <maintenance cost calculating part 1303> willbe described below, referring to FIG. 33 and FIG. 34.

Firstly, the job plan data is input to the job man-hour calculating partfrom the replacing timing plan database. Pipes to be replaced in eachwork year are determined by obtaining information on the job man-hourpart from the area 2002 and information on the replacing work timingfrom the area 2003 (replaced 1, not-replaced 0) (Process 3301).

It is determined from the job procedure data 1613 of the correspondingpipe using the work objective pipe ID as the key whether or not each ofthe process jobs is to be performed (job is required 1, job is notrequired 0). Then, each job man-hours is calculated using Equation 6(Process 3302).

Therein, the material data 1611 is input as the material amount of eachjob for each pipe, and the job cost data 1012 is searched and input asthe job cost for each job. As the result, each of the job man-hours andthe total job man-hours are output and stored in the job man-hourdatabase.

Further, the job man-hours required for the replacing jobs for all theselected pipes are individually summed for each of the jobs, and theresult are additionally recorded in the area 2901 of FIG. 29 (Process3303). Further, it is checked whether or not there are any omissiblework objective pipe, and omissible job man-hours are determined. Whetheror not each of the piping parts is omissible is determined according tothe flow shown in FIG. 36 (Process 3304). The total job man-hours aredetermined by subtracting the omissible jobs man-hours from theindividual job man-hours.

The non-operational period loss processing part determines the total ofthe each man-hours 2902 by receiving the job man-hour data of the area2901 (Process 3401), and determines work periods for individual jobsfrom the job man-hour vs. non-operational period table 1614 (Process3402), and outputs them as the job period data to be recorded as shownin FIG. 25.

This determining processing is performed as follows. Letting a jobman-hour be 10×A+B (A, B: integers, B<10), the first column 2501 of FIG.25 indicates A, and the first row 2502 indicates B. For example, aman-hour is 25, it is recognized that A=2, B=5 and the area 2503 in thefigure is regarded as the required work period.

The total maintenance cost determining processing part determines thejob man-hours for each job of the job man-hour database 1605, andcalculates the cost required for the job from the job days vs. job costtable 1615 using the job man-hour as the key.

This determining processing is performed similarly to the processingperformed by the job man-hour vs. non-operational period table. Lettinga job man-hour be 10×A+B (A, B: integers, B<10), the first column 2601of FIG. 26 indicates A, and the first row 2602 indicates B. For example,a man-hour is 25, it is recognized that A=2, B=5 and the area 2603 inthe figure is regarded as the required work cost, and the cost for eachjob is recorded in the memory 1503 (1607).

Next, the total job days is determined, and the electric power loss costduring work period is determined from the loss per day duringnon-operational period database using the total job days as the key(Process 3403).

This determining processing is performed similarly to the processingperformed by the job man-hour vs. non-operational period table. Lettinga job man-hour be 10×A+B+(A, B: integers, B<10), the first column 2701of FIG. 27 indicates A, and the first row 2702 indicates B. For example,a man-hour is 25, it is recognized that A=2, B=5 and the figure in thearea 2703 is regarded as the electric power loss cost, and the cost isrecorded in the memory 1503 (1607) in the form shown by FIG. 30.

Therein, the total cost of the piping parts is obtained by receivingcost 281 of the corresponding piping part from the material costdatabase 1617 using the pipe ID as the key, and by summing the costs forall the replaced pipes, and then recorded in the memory 1503 (1607) asthe total material cost as shown by FIG. 31 (Process 3403).

The work cost, the loss cost and the material cost stored in the memoryare processed as shown by Equation 8 to determine the total maintenancecost, and are recorded in the planned work plan cost database as shownby FIG. 32 by adding the individual cost 3202 to the work plan of FIG.20 (Process 3405).

Finally, the processing flow of the <optimum work plan determining part>will be described, referring to FIG. 17.

The lowest cost is searched from the cost column of the work plan caseclassification table 3201 stored in the planed work plan cost database1406 (Process 1701), and the plan is recorded in the optimum work plandatabase 1408.

The optimum work plan determining part can make a work plan whichmatches with an investment plan in maintenance by searching themaintenance cost for each work period from the maintenance plan storedin the planned work plan cost database.

Further, the optimum work plan determining part can make a work plan inwhich a used part or a part having a different lifetime for thereplacing piping part.

A minimum cost pipe replacing work plane will be made below, taking anactual plant piping line as an example.

A pipe line composed of three piping parts 1901, 1902 and 1903 in anuclear plant having a lifetime of 10 years is assumed, as shown by FIG.19. Description will be made on a detailed processing flow of this pipeline in which the processing automatically makes a maintenance plan andminimizes the maintenance cost during the plant servicing period.

The piping parts have pipe IDs of PIPE-1(1901), VAL-1(1902) andPIPE-2(1903), respectively.

It is assumed that a piping part having a minimum lifetime and thelifetime is 3 years are determined by searching deterioration data inthe pipe deterioration database 1402 using the pipe IDs as the key, andthat the work period is three years (that is, the work is carried out inthe first year, in the year 3 years after, in the year 6 years after,and in the year 9 years after). It is also assumed that the lifetimes ofthe piping parts are 3 years for PIPE-1(1901), 4 years for VAL-1(1902)and 9 years for PIPE-2(1903).

Cases whether or not VAL-1(1902) and/or PIPE-2(1903) are to be replacedis classified, and judgments whether or not there is necessity ofreplacement at n-th piping work period are stored in Table of FIG. 20.

This table classifies the cases that PIPE-1(1901) is to be replaced, andwhether or not VAL-1(1902) and/or PIPE-2(1903) are to be replaced.Replacing costs are calculated for each of the cases.

The first column of the table indicates combination number, the secondcolumn indicates the pipe IDs other than PIPE-1, and the third columnand the columns after that indicate the work carrying-out years (thefirst row) and presence-and-absence of replacing work for piping partsother than PIPE-1(1901), and the numerals (1) and (0) indicate that thepiping part is to be replaced and not replaced, respectively. In thisexample, number of the classified cases is 13, and the replacing planbecomes as shown by the table.

The pipe replacing plan No. 1 in the work plan case classification tableis input to the plant maintenance cost calculation part, and the costrequired for the pipe replacing plan No. 1 is calculated in the plantmaintenance cost calculation part to record the work cost in the costcolumn of the work plan case classification table. The similarprocessing is performed on the pipe replacing plan No.=2, 3, . . . , 13,each of the costs is calculated and recorded.

Further, it is assumed that the work plan No.=1 of FIG. 20 is outputfrom the replacing timing combination generating part. This work planand the material amount data are input into the job man-hour calculatingpart, and the job cost is determined by each of the pipes and each ofthe kinds of work. The job man-hour can be calculated by the following(equation 9) from the (equation 7). $\begin{matrix}{{{Job}\quad{man}\text{-}{hours}} = {\left( {\left( {{{job}\quad{cost}} = 18} \right)_{{scaffold}\quad{set}} \times \left( {{{material}\quad{amount}} = 2} \right)_{{scaffold}\quad{set}}} \right) + \left( {\left( {{{job}\quad{cost}} = 27} \right)_{cutting} \times \left( {{{material}\quad{amount}} = 1} \right)_{cutting}} \right) + \left( {\left( {{{job}\quad{cost}} = 24} \right)_{decontamination} \times \left( {{{material}\quad{amount}} = 8} \right)_{decontamination}} \right) + \left( {\left( {{{job}\quad{cost}} = 8} \right)_{disposition} \times \left( {{{material}\quad{amount}} = 3} \right)_{disposition}} \right) + \left( {\left( {{{job}\quad{cost}} = 25} \right)_{installation} \times \left( {{{material}\quad{amount}} = 3} \right)_{installation}} \right) + \left( {\left( {{{job}\quad{cost}} = 32} \right)_{welding} \times \left( {{{material}\quad{amount}} = 3} \right)_{welding}} \right) + \left( {\left( {{{job}\quad{cost}} = 6} \right)_{painting} \times \left( {{{material}\quad{amount}} = 3} \right)_{painting}} \right)}} & \left( {{Equation}\quad 9} \right)\end{matrix}$

Therefore, it is calculated that the first year work man-hours=300. Inthe case of this plan, since the similar work is to be performed 4 timesduring the plant lifetime, the total man-hour data becomes 300×4=1200.

The total man-hour data is input to the non-operational period lossprocessing part together with the job man-hour vs. non-operationalperiod table. The non-operational period loss processing part searchesthe job man-hours=1200 cell among the job man-hour vs. non-operationalperiod table, and outputs the corresponding job man-hours=2160 hours,that is, the job days=270 days, and calculates the work cost and theelectric power cost accompanied by the work.

Therein, it is also possible to calculate the job period required foreach procedure by using the job man-hours for each job procedure as theinput data.

Since the work cost and the electric power cost are determined by thejob man-hours and the job periods, the work cost and the electric powercost become 240 million yens and 96 million yens, respectively. On theother hand, it is assumed that the material costs are 1.00 million yensand 1.50 million yens for the pipes of PIPE-1, and -2, respectively, and3.00 million yens for the valve of VAL-1, the total material costbecomes 22.00 million yens because of 4 times of replacement.

Thus, it can be obtained from (Equation 8) that Workcost=2.200+240.00+96.00=358.00 (yens), and this result is stored in thecost column in the replacing timing plan database.

Finally, a plant maintenance work plan meeting with requirement of theclient is searched from the work plan and the cost of the work plan caseclassification table in the optimum work plan determining part, andstored in the selected maintenance plan database. When the clientrequests a minimum cost work plan, the plans No. 8 and No. 12 arerecorded in the selected maintenance plan database.

The series of the processing is performed on the 13 cases of thereplacing plans output from the replacing timing combination generatingpart. The plant maintenance costs for all the cases are calculated.

The reason why the total maintenance cost differs depending on the caseswill-be explained, taking the maintenance plan No. 6 as an example.

In the maintenance plan No. 6, the pipes to be replaced arePIPE-1(1901), VAL-1(1902) and PIPE-2(1903) in the first year, andPIPE-1(1901), VAL-1(1902) and PIPE-2(1903) in the year after 3 years,and PIPE-1(1901) and PIPE-2(1903) in the year after 6 years, andPIPE-1(1901) and VAL-1(1902) in the year after 9 years. Number of pipesto be replaced in the years after 6 years and 9 years is smaller, andaccordingly the material cost of the pipes and the job man-hour can bereduced.

Further, in the replacing work in the year after 9 years, the jobman-hours can be reduced because of the continuous positionalrelationship of the replaced pipes. On the other hand, since thereplaced pipes in the year after 6 years do not have the continuouspositional relationship, the job man-hours can not be reduced so much.

As described above, the difference between the costs during themaintenance is caused by the differences in the material cost of thepipe and the job man-hours.

Description will be made below on comparison between a conventionalmaintenance work cost in which the plant parts are taken one by one andthe maintenance work costs of the maintenance plans (No. 8 and No. 13)obtained from the present processing.

In the pipe line of FIG. 19, when the work plan is made through theconventional maintenance work cost in which the plant parts are takenone by one, the maintenance work must be performed 6 times, that is, inthe years after 0, 3, 4, 6, 8, and 9 years.

On the other hand, in the work plan according to the present processing,the maintenance work is performed only 3 times, that is, in the yearsafter 0, 3 and 6 years.

The electric power loss associated with stopping of plant operation canbe reduced nearly one-half by the present processing.

Therein, the pipe work plan can be divided into a replacing preparationjob from the scaffold setting to the piping part disposition; a mainwork from the installation to the welding; and the after settlement ofthe painting. The figure of the man-hours in the preparation work doesnot relate to the material amount. In other words, the man-hours when aplural number of piping part are replaced become nearly equal to thosewhen a single piping part is replaced.

The reason is that when a plural number of piping part are replaced,number of cut position can be reduced and the scaffold can be commonlyused. The decontamination job is not so much affected by the number ofthe piping parts. That is, the man-hours of the preparation job isnearly constant in each work regardless of the material amount.

Further, the costs required for the painting and the after settlementare nearly constant in each work. The work costs depending on thematerial amount are only the man-hours of the installation job and thewelding job.

The material cost is 14.50 million yens in the maintenance plan No. 8,but 13.50 million yens in the conventional maintenance work.

From the above, the equation calculating the total maintenance cost canbe also expressed as (Equation 10).Total maintenance cost=(preparation job cost+after settlement jobcost+loss cost due to stopping plant operation)×(number of worktimes)+(installation and welding job costs performed in eachyear)+(total material cost)   (Equation 10)

When numerical values for the conventional method and the present systemare substituted into (Equation 10), respectively, the following resultcan be obtained. $\begin{matrix}{\begin{matrix}{{Total}\quad{maintenance}\quad{cost}\quad{of}} \\{{the}\quad{conventional}\quad{method}}\end{matrix} = {\left( {22.20 + 3.60 + 24.00} \right) \times}} \\{6 + \left( {34.20 + 11.40 + 11.40 +} \right.} \\{\left. {11.40 + 11.40 + 22.80} \right) + 13.50} \\{= {414.90\quad{million}\quad{yens}}}\end{matrix}$ $\begin{matrix}{\begin{matrix}{{Total}\quad{maintenance}\quad{cost}\quad{of}} \\{{the}\quad{present}\quad{system}\quad{method}}\end{matrix} = {{\left( {22.20 + 3.60 + 24.00} \right) \times 4} +}} \\{\left( {34.20 + 22.80 + 34.20 +} \right.} \\{\left. 11.40 \right) + 14.50} \\{= {316.30\quad{million}\quad{yens}}}\end{matrix}$

Thus, the present processing can make a work plan more economical thanthat of the conventional method by 98.60 million yens.

According to the present invention, the predicted wall-thickness of thewhole pipe line can be accurately obtained.

Further, the wall-thickness of a piping part other than the piping partof which the wall-thickness is measured can be predicted.

Further, the wall-thickness of a pipe line not having the piping partsof which the wall-thickness is measured can be predicted.

Furthermore, by making replacing work plans using these predictedresult, more economical work can be performed.

1. A method of offering wall-thickness thinning prediction informationin which wall-thickness data of piping parts for specifyingwall-thickness values of the piping parts is received from a client, andsimulated wall-thickness data of the piping parts obtained based on thereceived wall-thickness data is offered to the client, the methodcomprising the steps of: simulating behavior of fluid flowing inside apipe line based on said received wall-thickness data of said pipingparts and three-dimensional layout data of said pipe line including saidpiping parts using a computer; calculating simulated wall-thickness dataof said piping parts composing said pipe line from change of saidsimulated behavior of fluid; and sending said simulated thinnedwall-thickness data to the client.